United Module Corporation, Inc.

Kinya Osa

When pixel signals included in pixel blocks forming an image are supplied, a detector detects the difference between pixel signal levels in the vicinity of block boundary of the pixel blocks. Then, a comparator compares the difference with a threshold value. An adder adds additional values to the pixel signal levels in the vicinity of block boundary in accordance with the comparison results. A pseudo random number is generated, to select a value pattern including the additional values from additional value patterns based on the random number. The above-described process can disturb the regularity of differentials in the pixel block boundary, thus positively facilitating to eliminate block deformation possibly arising in between pixel blocks.

Block deformation removing filter

A filter for removing block deformation that occurs in an image signal is disclosed. Detected are a plurality of differentials each between at least two pixel signal levels on block boundaries between pixel blocks and in the vicinity of the block boundaries in response to pixel signals included in a plurality of pixel blocks that form an image. The differentials are compared with each other to obtain the maximum differential absolute value. The maximum differential absolute value is compared with a reference value to determine whether block deformation occurs in a pixel signal in the vicinity of a position on the pixel blocks where the maximum differential absolute value is obtained. The block deformation is removed when it is determined that the block deformation occurs in the pixel signal in the vicinity of the position on the pixel blocks where the maximum differential absolute value is obtained. It is determined that the block deformation occurs when the maximum differential absolute value is smaller than the reference value. A specific value is added to the pixel signal in the vicinity of the position on the pixel blocks where the maximum differential absolute value is obtained when it is determined that the block deformation occurs. A value pattern with the specific value may be selected from a plurality of predefined value patterns based on random numbers. The selected pattern is added to the pixel signal in the vicinity of the position on the pixel blocks where the maximum differential absolute value is obtained.

Block deformation removing filter, image processing apparatus using the same, method of filtering image signal, and storage medium for storing software therefor

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Chiyoda-ku, Japan

Kinya Osa